classmethod(function)
中文說明：
classmethod是用來指定一個類別的方法為類別方法，沒有此參數指定的類別的方法為實例方法，使用方法如下：
class C:
@classmethod
def f(cls, arg1, arg2, ...): ...
類既可以直接類別呼叫(C.f())，也可以進行實例呼叫(C().f())。
版本：python2.2新增，在python2.4中增加新功能。 python3中仍可使用。
英文說明：
Return a class method for function.
A class method receives the class as implicit first argument, justike lri col 完成
class C:
@classmethod
def f(cls, arg1, arg2, ...): ...
The @classmethod form is a function decorator – see the description of function definitions in Function definitions for details.
) 🜒 class class class class。 on an instance (such as C().f()). The instance is ignored except for its class. If a class method is called for a derived class, the derived class object is passed as the implied first argument.🜟 Class methods are different than C++ or Java static methods. If you want those, see staticmethod() in this section.the hemage the hahhentation on class 類型, cons
New in version 2.2.
Changed in version 2.4: Function decorator syntax
